For example, an electric vehicle powered by an electric motor and a hybrid electric vehicle powered by a combustion engine and an electric motor mount the aforementioned power supply apparatus as a source for driving the electric motor. This power supply apparatus is provided with the bus bar module for series-connecting a plurality of battery cells (see the patent literature PTL 1).
The aforementioned conventional bus bar module, as illustrated in FIG. 6, is attached to the battery cell assembly fabricated by alternately and inversely stacking the battery cells each having a positive terminal at one end, and a negative terminal at the other end, and series-connects the battery cells being mutually stacked. The conventional bus bar module is configured to include a plurality of bus bars 103 arranged linearly in two rows so as to connect the plurality of battery cells in series-connection, a wiring-pattern portion 104 connected to each of the bus bars 103 and detecting a voltage of the each of the battery cells, a pair of insulative upper and lower films 105A and 105B (see FIG. 7) clamping the bus bars 103 arranged in two rows therebetween, and the wiring-pattern portion 104. FIG. 6 is a plan view of a conventional bus bar module 101, while FIG. 7 is an exploded perspective view of the conventional bus bar module shown in FIG. 6.
Each of the bus bars 103, as also illustrated in FIG. 7, is formed in a rectangular plate-like shape and configured to be formed having two insertion holes 103a into which terminals of the adjacent battery cells are inserted. The wiring-pattern portion 104 is configured to include a cupper foil being formed in a predetermined pattern on the one film 105A of the upper and lower films 105A and 105B. Through the upper and lower films 105A and 105B, a pair of communication holes 105a is formed at a location overlapping with the pair of insertion holes 103a of each bus bar 103.
Such a bus bar module 101 is integrally assembled in a state clamping the bus bars 103 and the wiring-pattern portion 104 by putting a vacuum press apparatus in operation between the upper and lower films 105A and 105B that are transparent resin films.
The bus bar module 101 thus assembled is brought to be attached to the battery cell assembly such that a plurality of nuts (not shown) is screwed with a terminal of each battery cell, in a state where being approximated to the upper surface to the battery cell assembly, and the terminals of the battery cells being inserted into the insertion holes 103a of the bus bars 103 and the communication hole 105a of the upper and lower films 105A and 105B to overlap with the upper surface of the battery cell assembly, to have each bus bar 103 electronically and mutually connect terminals of adjacent battery cells.